Have you ever noticed that if you're second or third in the last leg, you won't win?

Not true. Uchenna & Joyce in Season 7 were last all the way in the final leg, in the end, they had lucky karma which caused the airplane door not to close, allowing them to even up with Rob & Amber and for them to take the win.

And in Season 14, Margie & Luke were in the lead until Luke choked up in the surfboard roadblock...